fig1: Appending the WCA domain of Las17 to the endocytic cargo Ste2 rescues endosome motility in las17ΔWCA cells. Automated particle tracking was used to analyze endosome position over time. Ste2-GFP was used as an endosome marker in this and subsequent figures. The mean square displacement of endosomes (n = 50–100) over time was calculated for the indicated wild-type and mutant cells.

Mentions:
To obtain and analyze endosome motility more quantitatively, we used an automated particle tracking program developed to study actin patch motility in yeast (Carlsson et al., 2002). The resultant data were plotted as the mean squared displacement (MSD) of endosomes (n = 50–150) over time. This analysis indicated that endosomes labeled with Ste2-GFP were poorly motile in las17ΔWCA cells carrying an empty vector or a plasmid overexpressing Hxt1-WCA, as indicated by relatively flat curves in MSD plots (Fig. 1). In contrast, endosomes in the las17ΔWCA mutant expressing Ste2-WCA exhibited wild-type motility, as indicated by significantly greater displacement over time. Because under these conditions Ste2 is recruited to endosomes whereas Hxt1 is not, these results suggested that actin polymerization on endosomes rather than the plasma membrane promotes motility.

fig1: Appending the WCA domain of Las17 to the endocytic cargo Ste2 rescues endosome motility in las17ΔWCA cells. Automated particle tracking was used to analyze endosome position over time. Ste2-GFP was used as an endosome marker in this and subsequent figures. The mean square displacement of endosomes (n = 50–100) over time was calculated for the indicated wild-type and mutant cells.

Mentions:
To obtain and analyze endosome motility more quantitatively, we used an automated particle tracking program developed to study actin patch motility in yeast (Carlsson et al., 2002). The resultant data were plotted as the mean squared displacement (MSD) of endosomes (n = 50–150) over time. This analysis indicated that endosomes labeled with Ste2-GFP were poorly motile in las17ΔWCA cells carrying an empty vector or a plasmid overexpressing Hxt1-WCA, as indicated by relatively flat curves in MSD plots (Fig. 1). In contrast, endosomes in the las17ΔWCA mutant expressing Ste2-WCA exhibited wild-type motility, as indicated by significantly greater displacement over time. Because under these conditions Ste2 is recruited to endosomes whereas Hxt1 is not, these results suggested that actin polymerization on endosomes rather than the plasma membrane promotes motility.